Compact injector drive

ABSTRACT

In one embodiment, an injector includes a sleeve, a drive assembly, and a drive assembly housing. The sleeve is configured to receive a reservoir having a plunger therein. The drive assembly is configured to pressurize the reservoir and includes a tip, an actuator, and mechanical segments. The tip is configured to be secured to the plunger. The actuator is configured to supply a motive force to the tip for moving it between retracted and extended positions. The mechanical segments are configured to transmit motive force from the actuator to the tip. The drive assembly housing has a housing length in a direction parallel to a central longitudinal axis of the tip. The reservoir has a reservoir length L. A package length is defined by the housing length and the reservoir length L. The package length is less than 2L.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/588,577 filed Nov. 20, 2017, the contents of which are herebyincorporated by reference.

TECHNICAL FIELD

This disclosure generally relates to powered fluid injectors as well asrelated methods of pressurizing a fluid in a powered fluid injector.

BACKGROUND

Many medical procedures, including diagnostic and/or interventionalprocedures, involve injecting a contrast media into a patient.Angiography is one example of such a procedure. Angiography is used inthe diagnosis and treatment of cardiovascular conditions includingabnormalities or restrictions in blood vessels. During angiography, aradiographic image of the heart or vascular structure is obtained byinjecting contrast media through a catheter into a vein or artery of thepatient. The injected contrast media can pass to vascular structures influid communication with the vein or artery in which the injection ismade. Electromagnetic energy (e.g., X-rays, radio waves (e.g., magneticresonance imaging), or ultrasonic waves) is passed through the region ofthe body in which the contrast media was injected. This energy isabsorbed by the contrast media, causing a radiographic outline or imageof the blood vessel containing the contrast media.

An injector can be used to inject contrast media into a patient inconjunction with diagnostic and/or interventional medical procedures.Contrast media is generally held at the injector within a fluidcontainer, such as a reservoir. During a patient injection, the injectorpressurizes and delivers this contrast media to the patient. To do so,the injector generally drives a shaft linearly within the fluidcontainer, starting at one end of the fluid container and movingprogressively through the fluid container to an opposite end. So thatthe injector can deliver all of the contrast media in the fluidcontainer, the shaft generally has a fixed length extending in linearalignment with the fluid container at least equal to a length of thefluid container. Moreover, components used for linearly driving theshaft add to this length. Accordingly, a spatial profile created by thelength of the fluid container, shaft, and drive components can be morethan twice the length of the fluid container itself. Because space inthe vicinity of a patient undergoing a medical procedure can be at apremium, this size of a typical injector may be undesirable.

SUMMARY

In general, various exemplary embodiments relating to powered fluidinjectors, and related methods of pressurizing a fluid, are disclosedherein. These embodiments can be useful, for instance, by providing acompact powered fluid injector. This can be valuable since a compactpowered fluid injector can create additional available space in thevicinity of a patient undergoing a medical procedure. This additionalavailable space can accommodate medical personnel and/or other medicaldevices as needed for a particular medical procedure. Yet, the poweredfluid injector and related method embodiments disclosed herein can stillbe capable of providing operational functionality associated withtraditional, less compact injectors.

One exemplary embodiment includes a powered fluid injector. Thisexemplary powered fluid injector embodiment includes a sleeve, a driveassembly, and drive assembly housing. The sleeve is configured toreceive a reservoir that includes an inner reservoir diameter and areservoir length L defining an internal reservoir volume and a plungerwithin the internal reservoir volume. The drive assembly is configuredto pressurize the internal reservoir volume. The drive assembly includesa tip, an actuator, and a plurality of mechanical segments. The tip hasa central longitudinal axis and is configured to be secured to theplunger. The tip has a retracted position and an extended position. Theactuator is configured to supply a motive force to the tip for movingthe tip between the retracted and extended positions. The plurality ofmechanical segments are configured to transmit the motive force from theactuator to the tip. The drive assembly housing has a housing length ina direction parallel to the central longitudinal axis, a housing widthin a first direction perpendicular to the central longitudinal axis, anda housing height in a second direction perpendicular to the centrallongitudinal axis. The actuator is positioned within the drive assemblyhousing. The plurality of mechanical segments are positioned within thedrive assembly housing when the tip is in the retracted position. Thehousing length and the reservoir length L define a package lengthextending in the direction parallel to the central longitudinal axis.The package length is less than 2L.

In a further exemplary embodiment of this powered fluid injector, theplurality of mechanical segments includes a first segment portion and asecond segment portion. The first segment portion is along the centrallongitudinal axis of the tip and the second segment portion is offsetfrom the central longitudinal axis of the tip. The first and secondsegment portions can be positioned as such, for instance, when the tipis in the retracted position.

Another exemplary embodiment includes a method of pressurizing fluid ata powered fluid injector. This exemplary method embodiment includesactuating a drive assembly of the powered fluid injector to supply amotive force for moving a tip of the drive assembly between a retractedposition and an extended position. This tip is configured to be securedto a plunger that is within an internal volume of a reservoir. Theexemplary method further includes moving the tip from the retractedposition to the extended position by moving a portion of the driveassembly from a first location that is offset from a centrallongitudinal axis of the tip to a second location that is along thecentral longitudinal axis of the tip. The exemplary method also includesmoving the tip from the extended position to the retracted position bymoving the portion of the drive assembly from the second location to thefirst location.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings.

BRIEF DESCRIPTION OF DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not necessarily to scale (unless so stated) and areintended for use in conjunction with the explanations in the followingdescription. Embodiments of the invention will hereinafter be describedin conjunction with the appended drawings.

FIG. 1 is a perspective view of an exemplary embodiment of a poweredfluid injector.

FIG. 2 is a schematic, side elevational diagram of an exemplaryembodiment of a drive assembly housing for use in a powered fluidinjector.

FIG. 3 is a schematic, side elevational diagram of an exemplaryembodiment of a drive assembly for use in a powered fluid injector.

FIG. 4 is a schematic, side elevational diagram of another exemplaryembodiment of a drive assembly for use in a powered fluid injector.

FIG. 5 is a schematic, side elevational diagram of a further exemplaryembodiment of a drive assembly for use in a powered fluid injector.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, and/ordimensions are provided for selected elements. Those skilled in the artwill recognize that many of the noted examples have a variety ofsuitable alternatives.

FIG. 1 illustrates a perspective view of an exemplary embodiment of apowered fluid injector 100. In operation, the powered fluid injector 100can inject a quantity of fluid into a patient, for instance into avessel of a patient via a catheter. The fluid injected by the poweredfluid injector 100 can be, for example, a contrast fluid, a non-contrastfluid (e.g., saline), or a combination thereof. By injecting a quantityof fluid into a patient, the powered fluid injector 100 can facilitate avariety of medical diagnostic and/or interventional procedures. Theseprocedures can include, as examples, optical coherence tomography (OCT)imaging, intravascular ultrasound (IVUS) imaging, computed tomography(CT) imaging, magnetic resonance (MRI) imaging, angiographic procedures,and interventional device procedures/placements.

The illustrated powered fluid injector 100 includes a drive assemblyhousing 102 and a sleeve 104. The sleeve 104 can be secured to the driveassembly housing 102. For example, the drive assembly housing 102 caninclude an opening and the sleeve 104 can be secured to the driveassembly housing 102 at or near such opening. The sleeve 104 may extendout from the drive assembly housing 102 and may be configured to receiveand hold a reservoir 106. The reservoir 106 can have an internalreservoir volume containing a fluid and include a plunger 108 within theinternal reservoir volume. At least a portion of a drive assembly can behoused within the drive assembly housing 102. It is noted that the driveassembly housing 102 as shown in FIG. 1 is exemplary for purposes ofgenerally describing features of a powered fluid injector and detailsrelated to a powered fluid injector drive assembly housing will beexplained herein in reference to other figures. The drive assembly canbe configured to pressurize fluid within the internal reservoir volume.For instance, the drive assembly may couple to the plunger 108, such asat the opening in the drive assembly housing 102, and drive the plunger108 within the internal reservoir volume. As the plunger 108 isprogressively driven within the reservoir 106, fluid within the internalreservoir volume can be pressurized and output from the reservoir 106along tubing 109 leading to a patient. In certain applications of thepowered fluid injector 100, output fluid can be pressurized anywherefrom 1000-1500 psi (e.g., 1200 psi).

The illustrated embodiment of the powered fluid injector 100 includesseveral features that can be useful in pressurizing and delivering fluidduring operation. The powered fluid injector 100 can include a controlpanel 110. The control panel 110 can provide a user interface forvarious operational aspects. For example, the control panel 110 can beutilized by an operator to set up various parameters and/or protocols tobe used for a given fluid injection procedure. In one example, theoperator can interact with the control panel 110 to input injectionparameters such as flow rate, injection volume (e.g., maximum),injection pressure (e.g., maximum), rise time, and/or other injectionparameters. In one embodiment, control panel 110 includes a touch-screenpanel display, enabling an operator to view and modify injectionparameters. The control panel 110 can also be used to initialize poweredfluid injector 100 (e.g., to prepare it for a patient fluid injection),or to activate certain features or sequences of operation. The controlpanel 110 may also provide status information, including informationrelated to past or currently ongoing injection procedures as well as anyappropriate alerts. The control panel 110 can be controlled by one ormore processors (e.g., at the control panel 110 itself and/or within thedrive assembly housing 102). Such processors can also control othercomponents, such as the drive assembly, a peristaltic pump 112, whenpresent, and/or any sensors and detectors included at the powered fluidinjector 100.

In addition to the control panel 110, the illustrated powered fluidinjector 100 includes a hand-control device 113 for operator input. Thehand-control device 113 can be coupled to the control panel 110 eitherwirelessly or via a lined connection. Although, in other embodiments,the hand-control device 113 can be connected to a component of poweredfluid injector 100 other than control panel 110, such as drive assemblyhousing 102. The hand-control device 113 can generate and send varioussignals related to an injection procedure to the control panel 110 orother connected component. An operator can actuate one or more interfacecomponents at the hand-control device 113 to control an injectionprocedure. For example, the operator can use hand-control device 113 asa variable-rate control device to alter the fluid flow rate output fromthe powered fluid injector 100 and/or as a mechanism for starting orstopping an injection.

The powered fluid injector 100 can also include one or more componentsuseful for supplying fluid to be used in an injection procedure. Acontainer 114 can include a supply of fluid, such as contrast media, andbe secured to a holder 116 at the powered fluid injector 100. Fluid fromthe container 114 can be supplied to the reservoir 106 for use during aninjection procedure. For example, fluid from the container 114 can bedrawn into the reservoir 106 when the plunger 108 is being retracted(e.g., moved in a direction toward the drive assembly housing 102) andthereby refill the internal reservoir volume. Similarly, when thepowered fluid injector 100 includes the peristaltic pump 112, a secondcontainer 118 can include a supply of fluid, such as a flushing medium(e.g., saline), and be secured to a holder 120 at the powered fluidinjector 100. When present, the peristaltic pump 112 can receive fluidfrom the second container 118 and deliver such fluid to the patient.Often times, the peristaltic pump 112 may be used to delivernon-contrast fluid at a lower pressure than that at which the driveassembly delivers contrast fluid from the reservoir 106.

To facilitate delivery of fluid output from the reservoir 106 and/orperistaltic pump 112, the illustrated powered fluid injector 100includes a module 122. The module 122 can include a valving system 124to selectively place the reservoir 106 or peristaltic pump 112 incommunication with the patient. In one example, the valving system 124can include a manifold valve having a spring-biased spool valve, but inother examples various other types of valves, including check valves,can also be used. In one embodiment, when the valving system 124 is in afirst position fluid can flow from the reservoir 106 to a patient end126, but when valving system 124 is in a second position fluid can flowfrom the peristaltic pump 112 to the patient end 126. In this way, wherethe drive assembly outputs a relatively high pressure fluid (e.g.,contrast fluid at 1000-1500 psi) from the reservoir 106 and theperistaltic pump 112 provides a relatively low pressure fluid (e.g.,saline at 25-125 psi), the valving system 124 can selectively conveyfluid as appropriate for a particular sequence in an injectionprocedure.

FIG. 2 illustrates a schematic, side elevational diagram of an exemplaryembodiment of a drive assembly housing 202. The drive assembly housing202 is shown here relative to a reservoir 204 and a drive assembly 206.The components shown in FIG. 2 can be used as part of a powered fluidinjector, including the powered fluid injector described in reference toFIG. 1.

As shown here, a sleeve 208 can be secured to the drive assembly housing202. In the illustrated embodiment, the drive assembly housing 202includes an opening 210, and the sleeve 208 is secured at a region ofthe drive assembly housing 202 adjacent the opening 210. The sleeve 208can be configured to receive the reservoir 204 and thereby hold thereservoir 204 relative to the drive assembly housing 202. For instance,here the sleeve 208 defines a holding region that can be sized toreceive the reservoir 204 and this holding region is aligned with theopening 210 included at the drive assembly housing 202.

The reservoir 204 can include an internal reservoir volume 212. Theinternal reservoir volume 212 can be defined by an inner reservoirdiameter 214 and a reservoir length L. The reservoir length L can extendfrom an end of the reservoir 204 that interfaces with the drive assemblyhousing 202 to an opposite end of the reservoir 204 that interfaces withan outlet 216. Thus, the reservoir length L need not include a length ofthe outlet 216. The internal reservoir volume 212 can contain a fluidthat is to be pressurized and delivered via the outlet 216 to a patientduring an injection procedure. To facilitate fluid pressurization, aplunger 218 can be movably disposed within the internal reservoir volume212.

The drive assembly 206 can include a tip 220, an actuator 222, and aplurality of mechanical segments 224. The tip 220 has a centrallongitudinal axis 226 and can be configured to be secured to the plunger218. For instance, the plunger 218 can couple to the tip 220 when thereservoir 204 is received at the sleeve 208 and interfaces with thedrive assembly housing 202. A surface of the tip 220 may include one ormore connection features that removably mate with one or morecorresponding connection features on an interfacing surface of theplunger 218. The actuator 222 is positioned within the drive assemblyhousing 202 and is configured to supply a motive force for moving thetip 220. The plurality of mechanical segments 224 are configured totransmit motive force from the actuator 222 to the tip 220. In someembodiments, one of the mechanical segments 224 can be coupled to thetip 220, such as at a surface of the tip 220 that is opposite thesurface secured to the plunger 218, and the other mechanical segments224 may be coupled to one or more adjacent mechanical segments 224.Depending on the position of the tip 220, one or more (e.g., all) of theplurality of mechanical segments 224 may be positioned within the driveassembly housing 202.

The drive assembly 206 can be configured to pressurize the internalreservoir volume 212 by moving the tip 210, and thus the plunger 218,within the internal reservoir volume 212. To do so, the plurality ofmechanical segments 224 can transmit motive force from the actuator 222to the tip 220. This can act to move the tip 220 between a number ofpositions along the central longitudinal axis 226, including, forexample, between a retracted position 228 and an extended position 230.At the retracted position 228, the tip 220 can be, for instance, at ornear the drive assembly housing 202 (e.g., within the drive assemblyhousing 202) and the plurality of mechanical segments 224 may be withinthe drive assembly housing 202. At the extended position 230, the tip220 can be positioned closer to the outlet 216 than when at theretracted position 228 and one or more of the plurality of mechanicalsegments 224 can be moved out from the drive assembly housing 202. Asthe actuator 222 moves the tip 220 from the retracted position 228 tothe extended position 230, fluid within the internal reservoir volume212 can be pressurized and delivered via outlet 216. The actuator 222can also move the tip 220 in the opposite direction, from the extendedposition 230 to the retracted position 228.

The exemplary embodiment of the drive assembly housing 202 can have anumber of dimensions. Namely, the drive assembly housing 202 can have ahousing length HL, a housing width HW (shown in FIG. 1), and a housingheight HH. The housing length HL extends in a direction parallel to thecentral longitudinal axis 226. The housing width HW extends in a firstdirection perpendicular to the central longitudinal axis 226. Thehousing height HH extends in a second direction perpendicular to thecentral longitudinal axis 226.

Together, the housing length HL and the reservoir length L can define apackage length PL. The package length PL extends in a direction parallelto the central longitudinal axis 226. And, like the housing length HL,the reservoir length L extends in the direction parallel to the centrallongitudinal axis 226. The package length PL can be less than two timesthe reservoir length L (i.e., less than 2L). In some embodiments, thepackage length PL may be less than 1.9L, less than 1.75L, less than1.65L, or less than 1.5L. As shown in FIG. 2, the package length PL canbe measured as an extent in a direction parallel to the centrallongitudinal axis 226 defined by the reservoir length L and the housinglength HL. The package length PL measured as such may not necessarily beequal to a total of a measured reservoir length L plus a measuredhousing length HL. This can be the case when the package length PL isthe extent of these two components in the direction parallel to thecentral longitudinal axis 226 since any overlapping reservoir length Land housing length HL would account once for the extent in thisdirection, as is the case in the embodiment shown in FIG. 2. Thispackage length PL results in a relatively compact powered fluid injectoras compared to traditional, less compact injectors where a spatialprofile of the length of the fluid container, shaft, and drivecomponents can be more than twice the length of the fluid containeritself.

To allow for a compact powered fluid injector having the describedhousing length HL, and thus package length PL, a variety of driveassembly embodiments can be implemented. Examples of such drive assemblyembodiments are shown and described in reference to FIGS. 3-5.

FIG. 3 illustrates a schematic, side elevational diagram of an exemplaryembodiment of a drive assembly 300. As noted, the drive assembly 300 canbe used in a powered fluid injector to allow for a housing length, andthus package length, as described in reference to FIG. 2.

The drive assembly 300 includes a tip 302, an actuator 304, and aplurality of mechanical segments 306. The tip 302 has a centrallongitudinal axis 308 and can be configured to be secured to a plunger310 as described elsewhere herein. The actuator 304 is configured tosupply a motive force for moving the tip 302 via the plurality ofmechanical segments 306, which are configured to transmit motive forcefrom the actuator 304 to the tip 302. In operation, the drive assembly300 can be configured to pressurize an internal reservoir volume 312 ofa reservoir 314 by moving the tip 302, and thus plunger 310, within theinternal reservoir volume 312. The tip 302 is shown at a retractedposition 316 and in operation can be moved between a number of positionsalong the central longitudinal axis 308 as described elsewhere herein.

The plurality of mechanical segments 306 includes a first segmentportion 306 a, a second segment portion 306 b, and a third segmentportion 306 c. The first segment portion 306 a can be along the centrallongitudinal axis 308 while the second segment portion 306 b and thethird segment portion 306 c can be offset from the central longitudinalaxis 308. This may be the case, for example, when the tip 302 is at theretracted position 316 as shown in FIG. 3. For instance, when the tip302 is at the retracted position 316, the plurality of mechanicalsegments 306 may start at the central longitudinal axis 308 and becomeprogressively offset from the central longitudinal axis 308 by wrappingaround at least a portion of a point (e.g., within the drive assemblyhousing, such as the actuator 304). As shown in the example of FIG. 3,the plurality of mechanical segments 306 start at the centrallongitudinal axis 308 at approximately twelve o'clock on the point, herethe actuator 304, and wrap around this point to approximately sixo'clock where the plurality of mechanical segments 306 extend generallyparallel to the central longitudinal axis 308. While the point that theplurality of mechanical segments 306 are said to wrap around at least aportion of is the actuator 304 is this example, in other examples thepoint could be other select components or even an arbitrary point. Bywrapping the plurality of mechanical segments 306 around a point, thepackage length PL, can be reduced as compared to a drive assembly whichutilizes a ram, or other drive member, extending linearly along thecentral longitudinal axis of the drive assembly tip.

Thus, when the tip 302 is at the retracted position 316 in FIG. 3, theplurality of mechanical segments 306 may define a radius of curvaturethat approximates a radius of the actuator 304. At this position of thetip 302, the first segment portion 306 a may be tangent to a point, herethe actuator 304, at a first location, the second segment portion 306 bmay be tangent to the same point at a second location, and the thirdsegment portion 306 c may be tangent to the same point at a thirdlocation. The first, second, and third locations can all be differentfrom one another.

As noted, the first segment portion 306 a can be along the centrallongitudinal axis 308 while the second segment portion 306 b and thethird segment portion 306 c can be offset from the central longitudinalaxis 308. In particular, the third segment portion 306 c can be offsetfrom the central longitudinal axis 308 at an angular degree that isgreater than that at which the second segment portion 306 b is offsetfrom the central longitudinal axis 308. For instance, the second segmentportion 306 b can be offset from the central longitudinal axis 308 at anangle between zero and ninety degrees as measured from the centrallongitudinal axis 308 to a center point of the second segment portion306 b. As shown in the example here, the second segment portion 306 b isoffset from the central longitudinal axis 308 at an angle of about fortydegrees as measured from the central longitudinal axis 308 to a centerpoint of the second segment portion 306 b. The third segment portion 306c can be offset from the central longitudinal axis 308 at an angle ofninety degrees as measured from the central longitudinal axis 308 to acenter point of the third segment portion 306 c. As the tip 302 is movedfrom the retracted position 316, the first segment portion 306 a maystay along the central longitudinal axis 308 and the degree to which thesecond and third segment portions 306 b, 306 c are offset from thecentral longitudinal axis 308 may be reduced (e.g., the second and/orthird segment portion 306 b, 306 c may be moved into position along thecentral longitudinal axis 308).

In the illustrated embodiment of the drive assembly 300, each mechanicalsegment of the plurality of mechanical segments 306 is in the form of achain link member. Each chain link member can include a body 318. Insome cases, each chain link member can include a pair of opposingbodies. Though an example with one body 318 is shown in FIG. 3, in anexample utilizing a pair of opposing bodies, the other body of the pairof opposing bodies can be the same as the illustrated body 318. The body318 of a chain link member can have a first end 320 and a secondopposite end 322. As one example, the body 318 may have a central regionbetween the first and second ends 320, 322 that is of a reduced widthcompared to that at the first and second ends 320, 322. When a pair ofopposing bodies is used, the bodies can run parallel to one another andbe interconnected by a pin 323. One pin 323 can connect the pairopposing bodies at the respective first end 320 of the body 318 andanother pin 323 can connect the pair of opposing bodies at therespective second end 322 of the body 318.

In the drive assembly 300, each chain link member can be coupled to anadjacent chain link member to form the plurality of mechanical segments306. For instance, the first segment portion 306 a (in the form of achain link member) is coupled to the tip 302 at its first end and to anadjacent chain link member at its second end. Each of the second segmentportion 306 b and third segment portion 306 c (in the form of a chainlink member) is coupled to an adjacent chain link member at its firstend and to another adjacent chain link member at its second end. In oneexample, the pin 323 may serve to couple adjacent chain link memberstogether as shown in FIG. 3. In such an example utilizing a pair ofopposing bodies for each chain link member, the pin 323 can connectopposing bodies at a first end of a first chain link member, connectopposing bodies at a second end of a second chain link member, andcouple the first chain link member to the second chain link member.

In some embodiments, one or more of the plurality of mechanical segments306 can include a width that is substantially equal to an inner diameter325 of the reservoir 314. For example, one or more of the chain linkmembers can include an extension flange 324. The extension flange 324may extend out from the body 318 to define a largest extent of the widthof the chain link member. In the illustrated example, the extensionflange 324 extends out from the body 318 at each of two opposite edgesof the body 318. As one example, the extension flange 324 can extend outfrom the body 318 at each of the two opposite edges so that an extent ofthe extension flange 324, and thus width of the chain link member atthis location, is substantially equal to the inner diameter 325. Asshown in FIG. 3, certain of the chain link members include the extensionflange 324 extending out from the body 318 at each of two opposite edgesat the second end 322. In another embodiment, certain of the chain linkmembers can include an extension flange 324 extending out from the body318 at the first end 320, the second end 322, and/or the central region.

In the illustrated example, extension flanges 324 are included on some,but not all, of the plurality of mechanical segments 306. For example,extension flanges 324 can be included on those mechanical segmentportions forming a length of the plurality of mechanical segments 306that equals the reservoir length. In this way, when the tip 302 is movedto a fully extended position proximate an end of the reservoir 314,those mechanical segment portions that are moved into the reservoir 314can include extension flanges 324. When present, those mechanicalsegment portions that will not be brought into the reservoir 314 at anypossible position of the tip 302 may not include extension flanges 324.

To help support the plurality of mechanical segments 306 in the form ofchain link members, the drive assembly 300 may include a chain guide326. The chain guide 326 may be positioned within the drive assemblyhousing. In the illustrated example, the chain guide 326 has a first endlocated on the central longitudinal axis 308 (e.g., interfacing with theopening defined in the drive assembly housing and aligned with thesleeve) and a second opposite end that is offset from the centrallongitudinal axis 308 (e.g., by ninety degrees as measured from thecentral longitudinal axis 308 to a center point of the second end of thechain guide 326). The chain guide 326 can be configured to hold theplurality of mechanical segments 306 when they are within the driveassembly housing. In the illustrated example, the chain guide 326includes a first rail 328, a second rail 330, and a slot 332 definedbetween the first rail 328 and the second rail 330. The body 318 of eachchain link member may be positioned outside of the slot 332 and the pin323 may sit on, and move along, the slot 332. In this way, the first andsecond rails 328, 330, and slot 332, are configured to slidably receivethe pin 323. Similarly, if a chain link member includes the extensionflange 324, the extension flange 324 may also be positioned outside ofthe slot 332.

The actuator 304 is configured to use the plurality of mechanicalsegments 306 to transmit a motive force for moving the tip 302. To doso, the actuator 304 can engage one or more of the plurality ofmechanical segments 306 and thereby move the plurality of mechanicalsegments 306, in turn moving the tip 302. In the illustrated example,the actuator 304 includes a gear that has a surface 334 with a pluralityof teeth 336 spaced along the surface 334. The gear can be rotatablydriven by a power source and, when rotatably driven, the plurality ofteeth 336 are configured to mesh with a number of the plurality ofmechanical segments 306 to transmit motive force from the actuator 304to the tip 302. As one example shown in FIG. 3, respective ones of theplurality of teeth 336 may engage within the central region of the body318, or within a space defined between a pair of opposing bodies 318, ofcorresponding individual chain link members. For instance, in theillustrated example, the plurality of teeth 336 engage within the spacedefined between the pair of opposing bodies 318 of correspondingindividual chain link members and use the complimentary geometry of theplurality of teeth 336 and pins 323 to move the chain link members. InFIG. 3, the plurality of teeth 336 are configured to mesh with the firstsegment portion 306 a, in the form of a chain link member, along thecentral longitudinal axis 308. Also in FIG. 3, the plurality of teeth336 are configured to mesh with the second segment portion 306 b, in theform of a chain link member, at a location that is offset from thecentral longitudinal axis 308. In other embodiments, instead of a gear,the actuator 304 may be, for example, a fluid cylinder, stepper drive,or screw actuator.

The actuator 304 can be positioned within the drive assembly housing,for instance, at a location that is offset from the central longitudinalaxis 308 therein. Positioning the actuator 304 at a location offset fromthe central longitudinal axis 308 can be useful for a number of reasons.For example, this location of the actuator 304 may allow for a totallength of the plurality of mechanical segments 306 to be shortened ascompared to a total length that would be needed if the actuator 304 werepositioned along the central longitudinal axis 308. With this actuator304 location, the plurality of mechanical segments 306 can wrap aroundthe actuator 204 from a location that is offset from the centrallongitudinal axis 308 to a location that is along the centrallongitudinal axis 308, as shown in FIG. 3. As such, the plurality ofmechanical segments 306 can be brought into alignment with the centrallongitudinal axis 308 by the actuator 304 without needing to haveadditional length present for accommodating such alignment, as can bethe case if the actuator were positioned along the central longitudinalaxis 308. A shortened total length of the plurality of mechanicalsegments 306 may allow for a shortened drive assembly housing length. Asanother example, this location of the actuator 304 may be useful forsupporting certain of the plurality of mechanical segments 306 that areabout to enter the internal reservoir volume 312. This may createadditional stability and may help to prevent such mechanical segmentsfrom becoming misaligned at this time.

The drive assembly 300 can operate to move the tip 302, and thus plunger310, between a number of positions along the central longitudinal axis308. When operated, the actuator 304 can engage one or more of theplurality of mechanical segments 306 and thereby transfer motive forceto the plurality of mechanical segments 306. This moves the plurality ofmechanical segments 306 relative to reservoir 314.

For instance, when the drive assembly 300 is driven in a first operativemode, the plurality of mechanical segments 306 can be moved so as topush the tip 302 from the retracted position 316 to one or more extendedpositions. This can include moving the first segment portion 306 a alongthe central longitudinal axis 308 out from the drive assembly housingand into the internal reservoir volume 312. It can also include movingone or more other segment portions (e.g., the second and/or thirdsegment portion 306 b, 306 c) from one location that is offset from thecentral longitudinal axis 308 to another location that is along thecentral longitudinal axis 308. When a particular segment portion ismoved into the internal reservoir volume 312, the extension flange 324,when present, can support such segment portion against the innerdiameter wall of the reservoir 314.

Conversely, when the drive assembly 300 is driven in a second operativemode, the plurality of mechanical segments 306 can be moved so as topull the tip 302 from an extended position to the retracted position316. This can include moving the first segment portion 306 a along thecentral longitudinal axis 308 out from the internal reservoir volume 312and into the drive assembly housing. It can also include moving one ormore other segment portions (e.g., the second and/or third segmentportion 306 b, 306 c) from one location that is along the centrallongitudinal axis 308 to another location that is offset from thecentral longitudinal axis 308.

FIG. 4 illustrates a schematic, side elevational diagram of anotherexemplary embodiment of a drive assembly 400. The drive assembly 400 canbe used in a powered fluid injector to allow for a housing length, andthus package length, as described in reference to FIG. 2.

The drive assembly 400 includes a tip 402, an actuator 404, and aplurality of mechanical segments 406. The tip 402 has a centrallongitudinal axis 408 and can be configured to be secured to a plunger410 as described elsewhere herein. The actuator 404 is configured tosupply a motive force for moving the tip 402 via the plurality ofmechanical segments 406, which are configured to transmit motive forcefrom the actuator 404 to the tip 402. In operation, the drive assembly400 can be configured to pressurize an internal reservoir volume 412 ofa reservoir 414 by moving the tip 402, and thus plunger 410, within theinternal reservoir volume 412. The tip 402 is shown at a retractedposition 416 and in operation can be moved between a number of positionsalong the central longitudinal axis 408 as described elsewhere herein.

The plurality of mechanical segments 406 includes a first segmentportion 406 a, a second segment portion 406 b, and a third segmentportion 406 c. The first segment portion 406 a can be along the centrallongitudinal axis 408 while the second segment portion 406 b and thethird segment portion 406 c can be offset from the central longitudinalaxis 408. This may be the case, for example, when the tip 402 is at theretracted position 416 as shown in FIG. 4. For instance, when the tip402 is at the retracted position 416, the plurality of mechanicalsegments 406 may start at the central longitudinal axis 408 and becomeprogressively offset from the central longitudinal axis 408 by wrappingaround at least a portion of a point (e.g., within the drive assemblyhousing). In this example, the point that the plurality of mechanicalsegments 406 are said to wrap around at least a portion of is anarbitrary point within the drive assembly housing. As shown in theexample of FIG. 4, the plurality of mechanical segments 406 start at thecentral longitudinal axis 408 at approximately twelve o'clock on thepoint and wrap around this point to approximately six o'clock where theplurality of mechanical segments 406 extend generally parallel to thecentral longitudinal axis 408. Thus, when the tip 402 is at theretracted position 416 in FIG. 4, the first segment portion 406 a may betangent to the point at a first location, the second segment portion 406b may be tangent to the same point at a second location, and the thirdsegment portion 406 c may be tangent to the same point at a thirdlocation. The first, second, and third locations can all be differentfrom one another. By wrapping the plurality of mechanical segments 406around a point, the package length PL, can be reduced as compared to adrive assembly which utilizes a ram, or other drive member, extendinglinearly along the central longitudinal axis of the drive assembly tip.

As noted, the first segment portion 406 a can be along the centrallongitudinal axis 408 while the second segment portion 406 b and thethird segment portion 406 c can be offset from the central longitudinalaxis 408. In particular, the third segment portion 406 c can be offsetfrom the central longitudinal axis 408 at an angular degree that isgreater than that at which the second segment portion 406 b is offsetfrom the central longitudinal axis 408. For instance, the second segmentportion 406 b can be offset from the central longitudinal axis 408 at anangle between zero and ninety degrees as measured from the centrallongitudinal axis 408 to a center point of the second segment portion406 b. As shown in the example here, the second segment portion 406 b isoffset from the central longitudinal axis 408 at an angle of about fortydegrees as measured from the central longitudinal axis 408 to a centerpoint of the second segment portion 406 b. The third segment portion 406c can be offset from the central longitudinal axis 408 at an angle ofninety degrees as measured from the central longitudinal axis 408 to acenter point of the third segment portion 406 c. As the tip 402 is movedfrom the retracted position 416, the first segment portion 406 a maystay along the central longitudinal axis 408 and the degree to which thesecond and third segment portions 406 b, 406 c are offset from thecentral longitudinal axis 408 may be reduced (e.g., the second and/orthird segment portion 406 b, 406 c may be moved into position along thecentral longitudinal axis 408).

In the illustrated embodiment of the drive assembly 400, each mechanicalsegment of the plurality of mechanical segments 406 is in the form of aball member. Each ball member can include a body 418. The body 418 ofeach ball member can be shaped to facilitate low friction movement. Forinstance, the body 418 can include a three-dimensional rounded outersurface, such as in the shape of a sphere.

In the drive assembly 400, each ball member can be coupled to anadjacent ball member to form the plurality of mechanical segments 406.For instance, the first segment portion 406 a (in the form of a ballmember) is coupled to the tip 402 at its first end and to an adjacentball member at its second end. Each of the second segment portion 406 band third segment portion 406 c (in the form of a ball member) iscoupled to an adjacent ball member at its first end and to anotheradjacent ball member at its second end. In one embodiment, each ballmember can be coupled to an adjacent ball member by a cable 420. Forexample, the cable 420 may be coupled to the tip 402 at a first end,extend through an aperture 422 of each ball member, and terminate at afinal ball member at a second end. In another embodiment, each ballmember can be coupled to an adjacent ball member by a linkage element424. The linkage element 424 can be secured to two adjacent ballelements at an exterior surface of such ball elements using a pin 423. Alinkage element can also be used to couple the first segment portion 406a to the tip 402. In a further embodiment, ball members can be coupledto adjacent ball members using both the cable 420 and one or morelinkage elements.

In some embodiments, one or more of the plurality of mechanical segments406 can include a width that is substantially equal to an inner diameter425 of the reservoir 414. For example, one or more of the ball memberscan include a diameter that is substantially equal to the inner diameter425. This can allow the ball members moved within the internal reservoirvolume 412 to be supported against the inner diameter wall of thereservoir 314.

The drive assembly 400 may include a ball guide 426 supporting theplurality of mechanical segments 406 (in the form of ball members), forinstance when the plurality of mechanical segments 406 are not withinthe internal reservoir volume 412. The ball guide 426 may be positionedwithin the drive assembly housing. In the illustrated example, the ballguide 426 has a first end located on the central longitudinal axis 408(e.g., interfacing with the opening defined in the drive assemblyhousing and aligned with the sleeve) and a second opposite end that isoffset from the central longitudinal axis 408 (e.g., by ninety degreesas measured from the central longitudinal axis 408 to a center point ofthe second end of the ball guide 426). The ball guide 426 can beconfigured to hold the plurality of mechanical segments 406 when theyare within the drive assembly housing. In one example, the ball guide426 can form an enclosed sleeve within which the ball members can movewhen the tip 402 is at various positions. Accordingly, to accommodatethe ball members the ball guide 426 can have an interior diameter thatis substantially equal to the diameter of the ball members, and thussubstantially equal to the inner diameter 425 of the reservoir 414.Also, as shown in FIG. 4, the ball guide 426 includes a biasing member427, such as a compression spring, positioned thereat. In theillustrated example, the biasing member 427 is positioned at the secondend of the ball guide 426 so as to interface with a final ball member,for instance when the tip 402 is in the retracted position 416.

In the illustrated example, the actuator 404 includes a linear screwactuator configured to rotate, such as in a direction 428. An arm 430can connect the actuator 404 to a ball member. In particular, as shownhere, the arm 430 can include a fastener 432, such as a nut, at one endthat connects to the actuator 404. As an example, the fastener 432 caninclude internal threads configured to move linearly along correspondingthreads at the actuator 404 when the actuator 404 is rotated. The arm430 can further be secured at another end to a ball member, such as thefinal ball member as shown in FIG. 4.

The actuator 404 and the arm 430 can be positioned within the driveassembly housing, for instance, at a location that is offset from thecentral longitudinal axis 408 therein. Thus, in the illustrated example,the drive assembly 400 can include a number of mechanical segments(e.g., the second segment portion 406 b, the third segment portion 406c), the actuator 404, and the arm 430 positioned at a location that isoffset from the central longitudinal axis 408. This can be the case suchas when the tip 402 is at the retracted position 416. This can beuseful, for example, by allowing for a shortened drive assembly housinglength.

When the actuator 404 is rotatably driven, the arm 430 can be movedlinearly along a longitudinal axis of the actuator 404 and thereby actto move the plurality of mechanical segments 406. Accordingly, the driveassembly 400 can operate to move the tip 402, and thus plunger 410,between a number of positions along the central longitudinal axis 408.When operated, the actuator 404 can transfer motive force, such as viathe arm 430, to the plurality of mechanical segments 406 and therebymove the plurality of mechanical segments 406 relative to reservoir 414.

For instance, when the drive assembly 400 is driven in a first operativemode, the plurality of mechanical segments 406 can be moved so as topush the tip 402 from the retracted position 416 to one or more extendedpositions. This can include moving the first segment portion 406 a alongthe central longitudinal axis 408 out from the drive assembly housingand into the internal reservoir volume 412. It can also include movingone or more other segment portions (e.g., the second and/or thirdsegment portion 406 b, 406 c) from one location that is offset from thecentral longitudinal axis 408 to another location that is along thecentral longitudinal axis 408. Such first operative mode may includerotatably driving the actuator 404 in a first direction, such as thedirection 428, and thereby moving the arm 430 linearly in a firstdirection. Conversely, when the drive assembly 400 is driven in a secondoperative mode, the plurality of mechanical segments 406 can be moved soas to pull the tip 402 from an extended position to the retractedposition 416. This can include moving the first segment portion 406 aalong the central longitudinal axis 408 out from the internal reservoirvolume 412 and into the drive assembly housing. It can also includemoving one or more other segment portions (e.g., the second and/or thirdsegment portion 406 b, 406 c) from one location that is along thecentral longitudinal axis 308 to another location that is offset fromthe central longitudinal axis 308. Such second operative mode mayinclude rotatably driving the actuator 404 in a second direction, suchas opposite the direction 428, and thereby moving the arm 430 linearlyin a second direction.

FIG. 5 illustrates a schematic, side elevational diagram of a furtherexemplary embodiment of a drive assembly 500. The drive assembly 500 canbe used in a powered fluid injector to allow for a housing length, andthus package length, as described in reference to FIG. 2.

The drive assembly 500 includes a tip 502, an actuator 504, and aplurality of mechanical segments 506. The tip 502 has a centrallongitudinal axis 508 and can be configured to be secured to a plunger510 as described elsewhere herein. The actuator 504 is configured tosupply a motive force for moving the tip 502 via the plurality ofmechanical segments 506, which are configured to transmit motive forcefrom the actuator 504 to the tip 502. In operation, the drive assembly500 can be configured to pressurize an internal reservoir volume 512 ofa reservoir 514 by moving the tip 502, and thus plunger 510, within theinternal reservoir volume 512. The tip 502 is shown at a retractedposition 516 and in operation can be moved between a number of positionsalong the central longitudinal axis 508 as described elsewhere herein.

The plurality of mechanical segments 506 can include a number of segmentportions. For instance, the plurality of mechanical segments 506 caninclude a first segment portion 506 a, a second segment portion 506 b,and a third segment portion 506 c. The first segment portion 506 a canhave a first diameter, measured in a direction perpendicular to thecentral longitudinal axis 508. The second segment portion 506 b can havea second diameter, measured in the direction perpendicular to thecentral longitudinal axis 508. The third segment portion 506 c can havea third diameter, measured in the direction perpendicular to the centrallongitudinal axis 508. The second diameter of the second segment portion506 b can be greater than the first diameter of the first segmentportion 506 a, and the third diameter of the third segment portion 506 ccan be greater than the second diameter of the second segment portion506 b. Where included, other segment portions of the plurality ofmechanical segments 506 can be similar such that segment portiondiameters can be progressively greater moving away from the tip 502.

The plurality of mechanical segments 506 can be connected and form atelescoping member. The first segment portion 506 a can have a first end518 and a second end 520 defining a first segment portion lengththerebetween. The second end 520 can extend within the second segmentportion 506 b, for instance when the tip 502 is in the retractedposition 516 as shown in FIG. 5. Thus, the first diameter of the firstsegment portion 506 a can allow at least some of the first segmentportion length to nest within the second segment portion 506 b havingthe greater diameter. The second end 520 may be movably connected withinthe second segment portion 506 b. Likewise, the second segment portion506 b can have a first end 522 and a second end 524 defining a secondsegment portion length therebetween. The second end 524 can extendwithin the third segment portion 506 c, for instance when the tip 502 isin the retracted position 516 as shown in FIG. 5. Thus, the seconddiameter of the second segment portion 506 b can allow at least some ofthe second segment portion length to nest within the third segmentportion 506 c having the greater diameter. The second end 524 may bemovably connected within the third segment portion 506 c.

The actuator 504 can be configured to supply a motive force and therebydrive a telescoping sequence at the plurality of mechanical segments506. The actuator 504 may be coupled to the first segment portion 506 aand extend within the plurality of mechanical segments 506. In theillustrated embodiment, each of the plurality of mechanical segments 506is along the central longitudinal axis 508. When the actuator 504supplies a motive force, one or more of the plurality of mechanicalsegments 506 can be extended out from a nesting position within anadjacent segment as part of a telescoping extension sequence. Theactuator may also supply a motive force to retract one or more of theplurality of mechanical segment 506 to a nesting position within anadjacent segment as part of a telescoping retraction sequence.

For example, when the tip 502 is in the retracted position 516 and theactuator 504 begins to supply motive force in a telescoping extensionsequence, the first segment portion 506 a can extend out from a nestingposition within the second segment portion 506 b. This can result in thesecond end 520 of the first segment portion 506 a moving closer to thefirst end 522 of the second segment portion 506 b. The extent to whichthe first segment portion 506 a extends out may correspond to a degreeto which the tip 502 moves along the central longitudinal axis 508 fromthe retracted position 516. As the actuator 504 continues to supplymotive force, the second segment portion 506 b can extend out from anesting position within the third segment portion 506 c. In oneembodiment, the second end 520 of the first segment portion 506 a maycatch a corresponding structure of the second segment portion 506 b andthereby urge the second segment portion 506 b along the centrallongitudinal axis 508 and out from its nesting position. The extent towhich the second segment portion 506 b extends out may correspond to adegree of movement of the tip 502 along the central longitudinal axis508 in addition to movement resulting from the first segment portion 506a extending out.

As the described telescoping extension or retraction sequence takesplace, one or more of the plurality of mechanical segments 506 mayextend within the internal reservoir volume 512. Accordingly, the firstdiameter of the first segment portion 506 a, the second diameter of thesecond segment portion 506 b, and/or any other segment portion diametermay each be less than an inner reservoir diameter 525 of the reservoir514.

To supply motive force in a telescoping extension or retraction sequencebut yet provide a compact injector drive assembly, a number ofimplementations of the actuator 504 can be used. For example, theactuator 504 can include a leadscrew that translates applied rotationalforce, from a motor or other power source, into linear motion. Inanother example, the actuator can include a shaft having a number oftelescoping shaft segments that extend out from, or retract to, anesting position within an adjacent shaft segment.

In some cases, where a powered fluid injector utilizes the driveassembly 500, the speed at which consecutive segment portions of theplurality of mechanical segments 506 are extended out may be varied. Forexample, during a telescoping extension sequence the actuator 504 can beconfigured to extend the first segment portion 506 a out from thenesting position within the second segment portion 506 b at a firstspeed. Once the first segment portion 506 a has extended out from thenesting position within the second segment portion 506 b, the actuator504 can be configured to increase the speed at which the second segmentportion 506 b is extended out from the nesting position within the thirdsegment portion 506 c. The actuator 504 can be configured to increasethe speed at which the second segment portion 506 b is extended out to asecond speed that is greater than the first speed. Likewise, as thetelescoping extension sequence proceeds, the actuator 504 can beconfigured to progressively increase the speed at which each subsequentsegment portion is extended out from its respective nesting position. Avariable speed telescoping extension sequence can be useful in movingthe tip 502 from the retracted position to one or more extendedpositions in a manner that may output a consistent fluid flow rate.

In addition to the various powered fluid injector embodiments disclosedherein, embodiments relating to methods of pressurizing a fluid are alsowithin the scope of this disclosure. Such methods can include operatingone or more of the powered fluid injector embodiments described herein.

One exemplary embodiment includes a method of pressurizing a fluid in apowered fluid injector. This method embodiment includes actuating adrive assembly of the powered fluid injector to supply a motive forcefor moving a tip of the drive assembly between a retracted position andan extended position. The tip can be configured to be secured to aplunger that is within an internal volume of a reservoir. At theretracted position, the tip may be closer to a drive assembly housing ofthe powered fluid injector than when at the extended position. At theextended position, the tip may be closer to an outlet of the reservoirthan when at the retracted position. The powered fluid injector mayinclude a drive assembly housing within which an actuator of the driveassembly is positioned. The drive assembly housing can having a housinglength in a direction parallel to a central longitudinal axis of the tipand the reservoir may have a reservoir length L also in the directionparallel to the central longitudinal axis. The housing length and thereservoir length L can define a package length extending in thedirection parallel to the central longitudinal axis and the packagelength can be less than 2L.

The method embodiment also includes moving the tip from the retractedposition to the extended position. The tip is moved as such by moving aportion of the drive assembly from a first location that is offset fromthe central longitudinal axis of the tip to a second location that isalong the central longitudinal axis of the tip. In one example, this caninclude moving the portion of the drive assembly between one and ninetydegrees, as measured from the central longitudinal axis of the tip to acenter point of the portion of the drive assembly, to bring the portionof the drive assembly from the first location to the second location. Insome cases, the first location may be outside of a drive assemblyhousing of the powered fluid injector and the second location may beinside of the drive assembly housing of the powered fluid injector.

The method embodiment further includes moving the tip from the extendedposition to the retracted position by moving the portion of the driveassembly from the second location to the first location. In one example,this can include moving the portion of the drive assembly between oneand ninety degrees, as measured from the central longitudinal axis ofthe tip to a center point of the portion of the drive assembly, to bringthe portion of the drive assembly from the second location to the firstlocation. This might also include moving the portion of the driveassembly into the drive assembly housing.

Various examples have been described with reference to certain disclosedembodiments. The embodiments are presented for purposes of illustrationand not limitation. One skilled in the art will appreciate that variouschanges, adaptations, and modifications can be made without departingfrom the scope of the invention.

What is claimed is:
 1. A powered fluid injector comprising: a sleeveconfigured to receive a reservoir that includes an inner reservoirdiameter and a reservoir length L defining an internal reservoir volumeand a plunger within the internal reservoir volume; a drive assemblyconfigured to pressurize the internal reservoir volume, the driveassembly comprising: a tip having a central longitudinal axis andconfigured to be secured to the plunger, the tip having a retractedposition and an extended position, an actuator configured to supply amotive force to the tip for moving the tip between the retractedposition and the extended position, the actuator comprising a gearhaving a surface with a plurality of teeth spaced along the surface, anda plurality of mechanical segments configured to transmit the motiveforce from the actuator to the tip, the plurality of mechanical segmentscomprising a first chain link member and a second chain link member; anda drive assembly housing having a housing length in a direction parallelto the central longitudinal axis, a housing width in a first directionperpendicular to the central longitudinal axis, and a housing height ina second direction perpendicular to the central longitudinal axis,wherein the actuator is positioned within the drive assembly housing,and wherein the plurality of mechanical segments are positioned withinthe drive assembly housing when the tip is in the retracted position,and wherein the housing length and the reservoir length L define apackage length extending in the direction parallel to the centrallongitudinal axis and the package length is less than 2L, and whereinthe first chain link member is on the central longitudinal axis of thetip and the second chain link member is offset from the centrallongitudinal axis of the tip when the tip is in the retracted position,and wherein the plurality of teeth of the gear are configured to meshwith both the first chain link member and the second chain link memberwhen the tip is in the retracted position, and wherein the gear ispositioned such that the gear is configured to release the first chainlink member as the first chain link member enters the internal reservoirvolume when the tip is moved from the retracted position toward theextended position.
 2. The powered fluid injector of claim 1, whereineach mechanical segment of the plurality of mechanical segments has awidth equal to the inner reservoir diameter.
 3. The powered fluidinjector of claim 1, wherein the plurality of mechanical segmentsincludes a first segment portion along the central longitudinal axis anda second segment portion offset from the central longitudinal axis ofthe tip.
 4. The powered fluid injector of claim 3, wherein the pluralityof mechanical segments further includes a third segment portion offsetfrom the central longitudinal axis of the tip, the third segment portionbeing offset from the central longitudinal axis of the tip at an angulardegree that is greater than that at which the second segment portion isoffset from the central longitudinal axis of the tip.
 5. The poweredfluid injector of claim 4, wherein the second segment portion is offsetfrom the central longitudinal axis of the tip at an angle between zeroand ninety degrees as measured from the central longitudinal axis of thetip to a center point of the second segment portion and the thirdsegment portion is offset from the central longitudinal axis of the tipat an angle of ninety degrees as measured rom the central longitudinalaxis of the tip to a center point of the third segment portion.
 6. Thepowered fluid injector of claim 1, wherein the plurality of mechanicalsegments includes a plurality of chain link members including the firstchain link member and the second chain link member, each chain linkmember coupled to an adjacent chain link member to form the plurality ofmechanical segments.
 7. The powered fluid injector of claim 6, whereinthe drive assembly further comprises a chain guide supporting theplurality of mechanical segments.
 8. The powered fluid injector of claim1, wherein the gear is positioned at a location that is offset from thecentral longitudinal axis of the tip.
 9. A method of pressurizing afluid at a powered fluid injector, the method comprising the steps of:actuating a drive assembly of the powered fluid injector to supply amotive force for moving a tip of the drive assembly between a retractedposition and an extended position, the tip being configured to besecured to a plunger that is within an internal volume of a reservoir,the drive assembly further comprising an actuator for supplying a motiveforce to the tip for moving the tip between the retracted position andthe extended position and a plurality of mechanical segments fortransmitting the motive force from the actuator to the tip, the actuatorcomprising a gear having a surface with a plurality of teeth spacedalong the surface, the plurality of mechanical segments comprising afirst chain link member and a second chain link member; moving the tipfrom the retracted position to the extended position by engaging thefirst chain link member with at least one tooth of the plurality ofteeth of the gear at a first location that is offset from a centrallongitudinal axis of the tip and engaging the second chain link memberwith at least one tooth of the plurality of teeth of the gear a secondlocation that is along the central longitudinal axis of the tip, andwherein moving the tip from the retracted position to the extendedposition further comprises releasing the first chain link member fromthe at least one tooth of the plurality of teeth of the gear as thefirst chain link member enters the internal volume of the reservoir; andmoving the tip from the extended position to the retracted position bymoving the the second chain link member from the second location to thefirst location.
 10. The method of claim 9, wherein the gear ispositioned at a location that is offset from the central longitudinalaxis of the tip.
 11. The method of claim 9, wherein each mechanicalsegment of the plurality of mechanical segments has a width equal to aninner reservoir diameter of the reservoir.
 12. A powered fluid injectorcomprising: a sleeve configured to receive a reservoir that includes aninner reservoir diameter and a reservoir length L defining an internalreservoir volume and a plunger within the internal reservoir volume; adrive assembly configured to pressurize the internal reservoir volume,the drive assembly comprising: a tip having a central longitudinal axisand configured to be secured to the plunger, the tip having a retractedposition and an extended position, an actuator configured to supply amotive force to the tip for moving the tip between the retractedposition and the extended position, the actuator comprising a gearhaving a surface with a plurality of teeth spaced along the surface, anda plurality of mechanical segments configured to transmit the motiveforce from the actuator to the tip, the plurality of mechanical segmentscomprising a first chain link member and a second chain link member,wherein at least one of the first chain link member and the second chainlink member includes a body and an extension flange that extends outfrom the body to define a largest extent of a width of the at least oneof the first chain link member and the second chain link member, andwherein the extension flange is configured to support the at least oneof the first chain link member and the second chain link member againstthe internal reservoir diameter when the tip is in the extendedposition; and a drive assembly housing having a housing length in adirection parallel to the central longitudinal axis, a housing width ina first direction perpendicular to the central longitudinal axis, and ahousing height in a second direction perpendicular to the centrallongitudinal axis, wherein the actuator is positioned within the driveassembly housing, and wherein the plurality of mechanical segments arepositioned within the drive assembly housing when the tip is in theretracted position, and wherein the housing length and the reservoirlength L define a package length extending in the direction parallel tothe central longitudinal axis and the package length is less than 2L,and wherein the first chain link member is on the central longitudinalaxis of the tip and the second chain link member is offset from thecentral longitudinal axis of the tip when the tip is in the retractedposition, and wherein the plurality of teeth of the gear are configuredto mesh with both the first chain link member and the second chain linkmember when the tip is in the retracted position.
 13. The powered fluidinjector of claim 12, wherein the gear is positioned such that the gearis configured to release the first chain link member as the first chainlink member enters the internal reservoir volume when the tip is movedfrom the retracted position toward the extended position.
 14. Thepowered fluid injector of claim 12, wherein the drive assembly furthercomprises a chain guide supporting the plurality of mechanical segments.15. The powered fluid injector of claim 12, wherein the gear ispositioned at a location that is offset from the central longitudinalaxis of the tip.